Abrading implement

ABSTRACT

A mandrel includes a driving shank with an integral working head at one end which supports a disk assembly. The working head has a flat axially extending face on an annular lip which is formed by a generally circular axial recess in the head, and a threaded stud extends axially outwardly from the recess to receive the disk assembly. The disk assembly includes a disk of multiple abrasive coated plies held together by an internally threaded grommet disposed centrally within the disk. The grommet has a flange on one end and, on the other end, rivet tabs which are turned over on the disk to hold the plies in superposed relation, and the tabs are small enough to fit within the recess in noncontacting relation with the working head to provide for positive head-to-disk engagement solely between the face and the bottom ply of the disk. The arrangement prevents slipping of the disk relative to the mandrel.

United States Patent Field [4 1 Apr. 4, 1972 [54] ABRADING IMPLEMENT FOREIGN PATENTS OR APPLICATIONS [72] Inventor: Albert Field, c/o Field Abrasive Manufac- 666,035 2/ l952 Great Britain ..5l/378 turing Co., Inc., 1303 Stanley Avenue, Dayton, Ohio 45404 Primary Examiner-Donald G. Kelly An -M hl,Bbl,lh dB 22 Filed: Mar. 20, 1970 mm a e 21 Appl. No.: 21,387 ABSTRACT A mandrel includes a driving shank with an integral working 52 [1,5, (I s1 373, 5 40 head at one end which supports a disk assembly. The working 51 1m. (:1. ..B24d 13/08, B24d 13/14 head has a flat axially extending face on an annular p which is 58 Field of Search ..5l/376-378, 401, formed y a generally Circular axial recess in the head. and a 51/40 407 threaded stud extends axially outwardly from the recess to receive the disk assembly. The disk assembly includes a disk of 5 R f r cu multiple abrasive coated plies held together by an internally threaded grommet disposed centrally within the disk. The UNITED STATES PATENTS grommet has a flange on one end and, on the other end, rivet tabs which are turned over on the disk to hold the plies in sul 2F perposed relation, and the tabs are small enough to fit within 3 046 709 7/1962 C as) 51/378 the recess in non-contacting relation with the working head to 2'996852 8/1961 g"" 51/378 provide for positive head-to-disk engagement solely between the face and the bottom ply of the disk. The arrangement prevents slipping of the disk relative to the mandrel.

4 Claims, 3 Drawing Figures Patented April 4., 1972 FIG -2 lA/VE/VTOR ALBERT FIELD A TTOH/VEYS ABRADIN G IMPLEMENT BACKGROUND OF THE INVENTION In an abrading implement such as disclosed in U.S. Pat. No. 2,771,722, which issued to the predecessor of the assignee of the present invention, usually a mandrel is provided with a working head for supporting a disk assembly. Commonly, the disk comprises multiple abrasive coated plies of fabric or paper and is provided with a metal fitting for holding the plies in tight superposed relation and for connecting the assembly to the working head of the mandrel. Such multiple-ply abrading implements are used for deburring dies, metal patterns, welding spots and the like. Multiple plies are used to extend the service life of the disk, and the implements are usually used until all but one of the plies are ground down and are either manually torn off or are pulled off by the force of friction and heat.

The mounting of the disk assembly on the mandrel has presented a troublesome problem. The two parts are generally connected through a threaded arrangement between the fitting and the head, so that the metal fitting may be tightened down on the head. When the metal fitting is drawn down, it contacts the metal face of the mandrel which positively grips the fitting and rotates it through a metal-to-metal engagement. In turn, the multiple plies are rotated as well.

After a period of compressive use under this arrangement, the frictional drag applied to the plies through the workpiece often causes the plies to slip in the grommet, relative to the mandrel, and the efficiency of the implement is substantially diminished. There is a tendency for this to occur to some degree even if the fitting is provided with rivet tabs which dig into the plies and are intended to retard slippage.

SUMMARY OF THE INVENTION The present invention is directed to an improved abrading implement and mandrel for use with a disk of fabric plies. In general, the invention provides for a positive mandrel-to-disk engagement between the head and the bottom ply of the disk so that the mandrel is connected directly and solely to the plies and positively drives the plies rather than the fitting.

In accordance with a preferred embodiment of the inven-. tion, the mandrel has a'driving shaft and a working head, and the working head has a generally flat axial face on an annular lip which is formed by a generally circular axial recess in the head. A threaded stud extends from the recess outwardly of the annular lip and receives an internally threaded grommet, which holds the disk of multiple plies together.

The grommet is provided with rivet means at each end thereof which are turned over upon the body of the disk to hold the plies in tight superposed relation, and the rivet means are formed so that they will be disposed within the recess in non-contacting relation with the working head when the disk assembly is threaded onto the stud.

When so assembled, the bottom ply engages the axial face of the lip, and it is solely this connection which provides a metal-to-fabric engagement enabling the disk of plies to be positively driven by the mandrel. The torque generated by the power tool also tends to clamp the plies between the outer rivet means on the grommet and the axial face on the head. The arrangement serves to prevent slipping of the plies relative to the mandrel under the frictional forces set up by rotation of the implement against a workpiece.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevation, partly in section, showing the preferred embodiment of the present invention;

FIG. 2 is an exploded perspective view, partly in fragmentary section, showing the parts embodied in the preferred embodiment of the present invention, and

FIG. 3 is a view on line 33 in FIG. 1, partly in section and partly in elevation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the abrading implement 10 of the present invention includes a mandrel l1 and a disk assembly 12. The mandrel 11 is provided with a rotatable arbor or shank 13 which is adapted to be attached to the chuck of a hand drill or some other source of power for rotating the implement.

One end of the shank 13 is provided with an integral working head 14, and the end face of this head 14 has a circular recess 15 surrounded by an integral annular lip 16 having an end face 20, which is preferably flat. The mandrel l 1 includes an integral stud 22 which is threaded and extends centrally from the recess 15 outwardly beyond the face 20 on the flange 16, and as shown, the recess 15 is essentially in the form of a cylindrical ring formed around the base of the stud 22.

The disk assembly 12 includes multiple plies 25 of abrasive coated fabric or paper, each having a center hole 26, and a tubular metal grommet 30 which is internally threaded and has a flanged head 33. The plies 25 may be assembled with their abrasive surfaces all facing in the same direction, or in two groups facing outwardly in opposite directions, and after the grommet 30 is inserted through the aligned holes 26, its smaller end is riveted over at 35 upon the adjacent outermost ply to hold the plies in tight superposed relation.

As shown in FIG. 3, the rivet tabs 35 have a turned-over diameter which is smaller than the recess 15 so that they will be disposed within the recess 15 in non-contacting relation with the annular lip 16 when an exposed ply 25 is in contact with the face 20. The face 20 can therefore directly engage only the surface of the disk, and this arrangement is clearly shown in FIG. 1. In the preferred form of the invention, the flanged head 33, like the tabs 35, has a diameter which is also less than the inside diameter of the recess 15 so that the disk assembly 12 can be threaded on the stud 25 from either end of the grommet 30, in the case when half of the plies face in one direction and the other half face in the opposite direction.

Where the backing is paper, it is preferred that all of the plies be arranged with the abrasive facing outwardly, as shown in FIG. 2, for the reason that the paper plies are likely to tear off near the radial extremity of the flange 33, due to the relatively weak tear strength of paper. And the successive plies in the disk are likely to tear ofi along a diagonal line running through the disk from the radial extremity of the flange 33 to the radial extremity of the face 20. It would not be preferred practice, therefore, to reverse the disk assembly on the stud after some of the paper plies on one side have been used because the used plies, if torn off, would permit the grommet 30 to penetrate into the recess 15 and contact its base before the axial face 20 would contact the disk. Some fabric plies which are not likely to tear may be assembled in a back-to.- back arrangement because they merely tend to wear down at the point of contact with the workpiece, rather than tear. This arrangement is illustrated in FIG. 3, but generally the arrangement shown in FIG. 2 is preferred.

In accordance with the present invention, the working head 14 is formed to provide an essentially positive head-to-disk engagement between the flat face 20 and the adjacent ply 25 so that the rotary motion of the mandrel may be directly transferred solely to the disk, and, by virtue of the connection of the grommet to the disk, to the grommet 30 as well. Referring to FIG. 1, it can also be seen that a clamping action is established between the face 20 and the flange 33. This clamping feature is advantageously improved by the tightening action created by the torque of the power tool, which serves to move the grommet 30 an additional short distance into the recess 15, thereby increasing the ability of the mandrel 11 to transfer rotary motion directly to the disk of plies.

From the drawing and above description, it is apparent that an abrading implement in accordance with the invention provides desirable features and advantages. For example, the

direct head-to-disk engagement enables the mandrel 11 to rotate the entire disk assembly efiiciently solely thrcugh the plies, which contact the work. The arrangement of the present invention prevents the plies from slipping relative to the mandrel under the force of the frictional drag established between the workpiece and the outer ply, and therefore eliminates the problem of plies slipping relative to the mandrel and the grommet.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention, which is defined in the appended claims.

I claim:

1. An abrading implement comprising:

a. a mandrel having a working head at one end thereof,

b. means including an upstanding lip defining a recess extending axially into said working head,

c. an abrasive disk having portions defining a hole therethrough medially thereof,

d. grommet means extending through said hole and fastened to said abrasive disk with portions of said grommet overlying opposite faces of said disk,

e. means attaching said grommet to said working head with one of said overlying portions of said grommet received in said recess,

f. the thickness of said overlying portion of said grommet received in said recess being appreciably less than the height of said upstanding lip thereby maintaining said overlying portion of said grommet out of appreciable contact with said mandrel and frictionally engaging said lip into driving contact directly with said disk outwardly of said grommet.

2. The implement of claim 1 wherein:

a. said upstanding lip is substantially annular in configuration.

3. The implement of claim 2 wherein said attaching means comprises:

a. a threaded stud extending axially outwardly concentrically of said upstanding lip, and

b. means defining threads on an internal surface of said grommet complementary to the threads on said threaded stud.

4. The implement of claim 1 wherein said abrasive disk comprises:

a. a plurality of plies of abrasive coated backing material. 

1. An abrading implement comprising: a. a mandrel having a working head at one end thereof, b. means including an upstanding lip defining a recess extending axially into said working head, c. an abrasive disk having portions defining a hole therethrough medially thereof, d. grommet means extending through said hole and fastened to said abrasive disk with portions of said grommet overlying opposite faces of said disk, e. means attaching said grommet to said working head with one of said overlying portions of said grommet received in said recess, f. the thickness of said overlying portion of said grommet received in said recess being appreciably less than the height of said upstanding lip thereby maintaining said overlying portion of said grommet out of appreciable contact with said mandrel and frictionally engaging said lip into driving contact directly with said disk outwardly of said grommet.
 2. The implement of claim 1 wherein: a. said upstanding lip is substantially annular in configuration.
 3. The implement of claim 2 wherein said attaching means comprises: a. a threaded stud extending axially outwardly concentrically of said upstanding lip, and b. means defining threads on an internal surface of said grommet complementary to the threads on said threaded stud.
 4. The implement of claim 1 wherein said abrasive disk comprises: a. a plurality of plies of abrasive coated backing material. 